Quote:
Returns or sets the width of all columns in the specified range. Read/write Variant.
Remarks
One unit of column width is equal to the width of one character in the Normal style. For proportional fonts, the width of the character 0 (zero) is used.
Use the Width property to return the width of a column in points.
If all columns in the range have the same width, the ColumnWidth property returns the width. If columns in the range have different widths, this property returns Null.
If you just want to find the widest piece of text then you can loop through the cells checking the length and storing the value if it is the largest you have found so far. I'm not sure how you determine the width of a section of text in a non-fixed-pitch font.